
main(List<String> args) {
  // 1. 定义字符串 '', "", """ 可以换行  """
  var str1 = '123';
  var str2 = "456";
  var str3 = """
  123
  456
  """;
  // 2. 字符串 和表达式拼接 ${}, runtimeType 获取类型
  var name = "shy";
  var age = 19;
  var height = 1.88;

  var message1 = "my name is ${name}, age is ${age}, height is ${height}";
  print(message1);
}